Video encoding/decoding system and diagnosis method thereof

ABSTRACT

A video encoding/decoding system includes a video encoding device and a video decoding device. The video encoding device includes an encoding part for encoding a diagnostic image or normal image. The video decoding device includes a decoding part for decoding the image encoded by the encoding part, a check signal generation part for generating a check signal of the decoded image, a storage part for storing the expected value of the check signal of the diagnostic image or the check signal generated by the check signal generation part, and a comparison part for comparing the check signal stored in the storage part with the check signal generated by the check signal generation part, in order to detect failure in all the paths from the image input part of the video encoding device to the image output part of the video decoding device.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2015-001530 filed onJan. 7, 2015 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a video encoding/decoding system, andis applicable, for example, to a video encoding/decoding system withfailure detection function.

Driver support function and automated driving function for vehicles havebeen put into practice in recent years. In a system including anin-vehicle camera and an image analysis device for the purpose ofdetecting obstacles or other purposes, the resolution of the images tobe handled has been increased to achieve a high precision. Because ofthis, digital video transmission using image compression techniques hasbeen widely used. A high level of safety is required for the driversupport function and automated driving function. Thus, it is necessaryto use a method that can detect failure in the video encoding device,the transmission path of the compressed image, and the video decodingdevice. There have been proposed failure detection techniques, forexample, as disclosed in Japanese Unexamined Patent ApplicationPublication Nos. 2006-148430 (Patent Document 1) and 2008-546338 (PatentDocument 2), as well as in the corresponding U.S. Pat. No. 8,457,199(Patent Document 3).

Patent Document 1 describes the following: “The technique is an imagerecording device for compressing a digitally converted video signal inan image compression part 6, extending data recoded in a hard diskrecording part 11, and outputting the extended data. The image recordingdevice includes an ROM 9 for recoding a reference data as well as a testdata generation part 3, in which the data of the test data generationpart 3 is compressed and stored in the image compression part 6. Thecompressed test data is compared with the reference data. The data ofthe test data generation part 3 is stored in an RAM 10 to compress andstore in the image compression part 6. Then, the reference data of theROM 9 and the test data compressed in the RAM 10 are compared with eachother to determine whether the data is normal or not, in order toperform self-diagnosis to check the fact that abnormality occurred ineither the hard disk recording part 11 or the image compression part 6.”

Patent Document 2 describes the following technique: “In a transmitter,a video signal is encoded by generating a differential signal (in 2),showing the difference between the transmission image and the predictedimage based on the image that is stored and partially decoded. Thedifferential signal is decoded to generate a new partially decodedimage. The transmitter also generates a check signal, such as CRC, whichis used as a function of the partially decoded image. A receiver decodesthe differential signal and generates a decoded image. Then, thereceiver compares the decoded image with the check signal. If the two donot match, the receiver generates an error signal.”

SUMMARY

The self-diagnosis described in Patent Document 1 can detect failure inthe image compression part but may not detect failure in the imageextension part. Further, the reference data is a bit stream with a largesize, so that a large capacity ROM is required and the cost is high. Inaddition, the test data/expected value can be huge in order to obtainsufficient coverage. As a result, it is difficult to detect soft errors.

In the error detection system described in Patent Document 2 or 3, CRCcodes generated by the respective image encoder and the decoder aregenerated from the output of the encoder. For this reason, the CRC codeswill match even if the output of the encoder is an erroneous result dueto a failure. In addition, the transmission of the CRC code from theimage encoder to the decoder consumes an extra bandwidth of thetransmission path.

An object of the present invention is to provide a technology that candetect failure in all the paths from the image input part of the videoencoding device to the image output part of the video decoding device.

Other objects, advantages and novel features of the invention willbecome more apparent from the following detailed description of theinvention when taken in conjunction with the accompanying drawings.

A typical one of the aspects of the present invention will be brieflydescribed below.

In other words, in a video encoding/decoding system, an image that isdecoded by a video encoding device is decoded by a video decoding devicein order to detect failure based on a check signal generated from thedecoded image and on a check signal stored in advance.

According to the video encoding/decoding system, it is possible todetect failure in all the paths from the image input part of the videoencoding device to the image output part of the video decoding device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a video encoding/decoding systemaccording to an embodiment;

FIG. 2 is a schematic diagram showing a first failure detectionoperation of the video encoding/decoding system according to theembodiment;

FIG. 3 is a schematic diagram showing a second failure detectionoperation of the video encoding/decoding system according to theembodiment;

FIG. 4 is a schematic diagram showing a third failure detectionoperation of the video encoding/decoding system according to theembodiment;

FIG. 5 is a block diagram showing the video encoding/decoding systemaccording to an example;

FIG. 6 is a block diagram showing a video encoding device according toan example;

FIG. 7 is a block diagram showing a video decoding device according tothe example;

FIG. 8 is a timing diagram showing the second failure detectionoperation of the video encoding/decoding system according to theexample;

FIG. 9 is a timing diagram showing the effect of the second failuredetection operation of the video encoding/decoding system according tothe example;

FIG. 10 is a timing diagram showing the effect of the second failuredetection operation of the video encoding/decoding system according tothe example;

FIG. 11 is a timing diagram showing the third failure detectionoperation of the video encoding/decoding system according to theexample;

FIG. 12 is a timing diagram showing the third failure detectionoperation of the video encoding/decoding system according to theexample;

FIG. 13 is a timing diagram showing the operation that combines thefirst and second failure detection operations of the videoencoding/decoding system according to an example;

FIG. 14 is a timing diagram showing the operation with a combination ofthe first failure detection operation of the video encoding/decodingsystem according to the example;

FIG. 15 is a timing diagram showing the operation with a combination ofthe first and third failure detection operations of the videoencoding/decoding system according to an example;

FIG. 16 is a block diagram showing a video encoding/decoding systemaccording to Application Example 1;

FIG. 17 is a block diagram showing a video encoding/decoding systemaccording to Application Example 2;

FIG. 18 is a block diagram showing a video encoding/decoding systemaccording to Application Example 3; and

FIG. 19 is a block diagram showing a video encoding/decoding systemaccording to Application Example 4.

DETAILED DESCRIPTION

Hereinafter, the preferred embodiment, example, and applications will bedescribed with reference to the accompanying drawings. Note, however,that in the following description the same components are denoted by thesame reference numerals and the redundant description thereof may beomitted.

Embodiment

First, a video encoding/decoding system according to an embodiment willbe described with reference to FIGS. 1 to 4. FIG. 1 is a block diagramshowing the configuration of a video encoding/decoding system accordingto the embodiment. FIG. 2 is a schematic diagram showing an example of afirst failure detection operation of the video encoding/decoding systemaccording to the embodiment. FIG. 3 is a schematic diagram showing anexample of a second failure detection operation of the videoencoding/decoding system according to the embodiment. FIG. 4 is aschematic diagram showing an example of a third failure detectionoperation of the video encoding/decoding system according to theembodiment.

As shown in FIG. 1, a video encoding/decoding system 100 according tothe embodiment includes a video encoding device 10 and a video decodingdevice 20. The video encoding device 10 includes an encoding part 11 forending an image. The video decoding device 20 includes: a decoding part21 for decoding the encoded image; a check signal generation part (CSG)22 for generating a check signal from the decoded image; a storage part23 for storing the check signal; and a comparison part (CMP) 24 forcomparing the check signal generated by the check signal generation part22 with the check signal stored in the storage part 23.

It is preferable that the video encoding device 10 further includes adiagnostic image generation part 12 for generating a diagnostic image(TEST PICTURE), as well as a switching circuit 13 for switching betweenthe input image (INPUT PICTURE) and the diagnostic image.

The video encoding/decoding system 100 performs a failure detectionoperation (diagnosis) by one or a combination of the followings.

(1) First Failure Detection Operation (First Diagnosis)

The encoding part 11 encodes (compresses) a diagnostic image output fromthe diagnostic image generation part 12 in a predetermined order, andtransmits to the video decoding device 20. The decoding part 21 decodes(extends) the encoded image received from the video encoding device 10,and generates a check signal of the decoded image. The comparison part24 compares the check signal generated by the check signal generationpart 22 with the expected value (check signal of the diagnostic image)which is stored in advance in the storage part 23. If the comparisonresult is a mismatch, the comparison part 24 determines that a failurehas occurred, and outputs (or activates) the failure detection signal.

An example of the first failure detection operation will be describedwith reference to FIG. 2. It is assumed that failure detectionoperations from A image, B image, C image, D image, E image, and F imagefor diagnosis are T(A), T(B), T(C), T(D), T(E), and T(F). In T(A), thediagnostic image generation part (TPG) 12 outputs an A image fordiagnosis. Then, the encoding part (ENC) 11 generates an a image byencoding the A image. The decoding part (DEC) 21 generates the A imageby decoding the a image. Then, the check signal generation part (CSG) 22generates a check signal (A_C) of the A image. The comparing part (CMP)24 compares the check signal (A_C) of the A image, which is the expectedvalue stored in the storage part (MEM) 23, with the check signal (A_C)of the A image that is generated by the check signal generation part 22.In this case, the check signals (A_C) match, so that the comparison part24 does not output (or inactivates) the failure detection signal.Similarly, the check signals match in the operations from T(B) to T(E),so that the comparison part 24 does not output (or inactivates) thefailure detection signal.

In T(F), the diagnostic image generation part (TPG) 12 generates an Fimage for diagnosis. Then, the encoding part (ENC) 11 generates an fimage by encoding the F image. Due to a failure in the decoding part(DEC) 21, the decoding part (DEC) 21 generates an R image by decodingthe f image. Then, the check signal generation part (CSG) 22 generates acheck signal (R_C) of the R image. The comparison part (CMP) 24 comparesthe check signal (F_C) of the F image, which is the expected valuestored in the storage part (MEM) 23, with the check signal (R_C) of theR image that is generated by the check signal generation part 22. Inthis case, the check signals do not match, so that the comparison part24 outputs (or activates) the failure detection signal.

(2) Second Failure Detection Operation (Second Diagnosis)

The diagnostic image generation part 12 randomly generates a diagnosticimage. The encoding part 11 encodes the output diagnostic image, andtransmits the encoded image to the video decoding device 20. Thedecoding part 21 decodes the encoded image received from the videoencoding device 10. Then, the check signal generation part 22 generatesa check signal of the decoded image. After the encoding-decodingoperation is performed twice on the same diagnostic image, thecomparison part 24 detects a failure by checking a match between thefirst check signal of the decoded image stored in the storage part 23,and the second check signal of the decoded image stored in the storagepart 23. If the comparison result is a mismatch, the comparison part 24determines that a failure has occurred and outputs (or activates) thefailure detection signal.

An example of the second failure detection operation will be describedwith reference to FIG. 3. It is assumed that the first and secondfailure detection operations from the A image, B image, and C image fordiagnosis are T(A1), T(A2), T(B1), T(B2), T(C1), and T(C2). In T(A1),the diagnostic image generation part (TPG) 12 generates an A image fordiagnosis, and the encoding part (ENC) 11 generates an a image byencoding the A image. The decoding part (DEC) 21 generates the A imageby decoding the a image. Then, the check signal generation part (CSG) 22generates a check signal (A_C) of the A image and stores in the storagepart (MEM) 23. In T(A2), the diagnostic image generation part (TPG) 12outputs the A image for diagnosis, which is the same image as in T(A1).Then, the encoding part (ENC) 11 generates an a image by encoding the Aimage. The decoding part (DEC) 21 generates the A image by decoding thea image. Then, the check signal generation part (CSG) 22 generates thecheck signal (A_C) of the A image. The comparison part (CMP) 24 comparesthe first check signal of the A image that is stored in the storage part(MEM) 23 with the second check signal (A_C) of the A image that isgenerated by the check signal generation part 22. In this case, thecheck signals (A_C) match, so that the comparison part 24 does notoutput (or inactivates) the failure detection signal. Similarly, thecheck signals match in T(B2), so that the comparison part 24 does notoutput (or inactivates) the failure detection signal.

In T(C1), the diagnostic image generation part (TPG) 12 generates a Cimage for diagnosis. Then, the encoding part (ENC) 11 generates a cimage by encoding the C image. The decoding part (DEC) 21 generates theC image by decoding the c image. Then, the check signal generation part(CSG) 22 generates a check signal of the C image and stores in thestorage part (MEM) 23. In T(C2), the diagnostic image generation part(TPG) 12 outputs the C image for diagnosis, which is the same image asin T(C1). Then, due to a failure in the encoding part (ENC) 11, theencoding part (ENC) 11 generates an f image by encoding the C image. Thedecoding part (DEC) 21 generates the F image by decoding the f image.Then, the check signal generation part (CSG) 22 generates a check signal(F_C) of the F image. The comparison part (CMP) 24 compares the firstcheck signal (C_C) of the C image that is stored in the storage part(MEM) 23 with the second check signal (F_C) of the F image that isgenerated by the check signal generation part 22. In this case, thecheck signals do not match, so that the comparison part 24 outputs (oractivates) the failure detection signal.

(3) Third Failure Detection Operation (Third Diagnosis)

Different from the first and second failure detection operations, thethird failure detection operation performs failure detection by a normalvideo encoding/decoding operation (normal operation). In other words, inthe normal operation, part or whole of the input image as well asencoding parameters are stored in the encoding part 11, and a checksignal of a decoded image is generated and stored in the storage part23. The same operation is performed again to obtain a check signal ofthe decoded image. Then, the obtained two check signals are compared bythe comparison part 24. If the comparison result is a mismatch, thecomparison part 24 determines that a failure has occurred.

An example of the third failure detection operation will be describedwith reference to FIG. 4. It is assumed that the first and secondfailure detection operations from the normal A image, B image and Cimage are T(A1), T(A2), T(B1), T(B2), T(C1), and T(C2). In T(A1), theencoding part (ENC) 11 generates an a image by encoding the input Aimage. Here, the image data or other information necessary for thesecond encoding is stored in an image storage part (PICB) not shown. Thedecoding part (DEC) 21 generates the A image by decoding the a image.Then, the check signal generating part (CSG) 22 generates a check signal(A_C) of the A image and stores in the storage part (MEM) 23. In T(A2),the encoding part (ENC) 11 generates an a image by encoding the A imagestored in PICB. The decoding part (DEC) 21 generates the A image bydecoding the a image. Then, the check signal generation part (CSG) 22generates a check signal (A_C) of the A image. The comparison part (CMP)24 compares the first check signal (A_C) of the A image that is storedin the storage part (MEM) 23, with the check signal (A_C) of the A imagethat is generated by the check signal generation part 22. In this case,the check signals (A_C) match, so that the comparison part 24 does notoutput (or inactivates) the failure detection signal. Similarly, thecheck signals match in T(B2), the comparison part 24 does not output (orinactivates) the failure detection signal.

In T(C1), the encoding part (ENC) 11 generates a c image by encoding theinput C image. Here, the image data or other information necessary forthe second encoding is stored in PICB. The decoding part (DEC) 21generates the C image by decoding the c image. Then, the check signalgeneration part (CSG) 22 generates a check signal (C_C) of the C imageand stores in the storage part (MEM) 23. In T(C2), the encoding part(ENC) 11 generates an f image by encoding the C image stored in PICB dueto a failure. The decoding part (DEC) 21 generates the F image bydecoding the f image. Then, the check signal generation part (CSG) 22generates a check signal (F_C) of the F image. The comparison part (CMP)24 compares the first check signal (C_C) of the C image that is storedin the storage part (MEM) 23 with the second check signal (F_C) of the Fimage that is generated by the check signal generation part 22. In thiscase, the check signals do not match, so that the comparison part 24outputs (or activates) the failure detection signal.

In the video encoding/decoding system 100, it is possible to detectfailure in all the paths from the image input part of the encoding part11 of the video encoding device 10 to the image output part of thedecoding part 21 of the video decoding device 20. In addition, anyadditional information such as a check signal is not transmitted fromthe video encoding device 10, so that the extra bandwidth of thecommunication path (transmission path) is not consumed.

In the first failure detection operation, the expected value is thecheck signal whose size is smaller than the bit stream, so that thestorage cost is low.

In the second failure detection operation, the coverage of the failuredetection is increased by the use of numerous diagnostic images. At thesame time, there is no need to use expected values and the storagecapacity of the storage part 23 can be reduced. As a result, the cost ofstoring expected values is lower than that in the first failuredetection operation.

In the third failure detection operation, as compared to the first andsecond failure detection operations, the operation exclusive for failuredetection is not required, so that the power consumption is reduced.Further, different from the first and second failure detectionoperations, the failure detection is performed during the normaloperation, making it possible to detect soft errors.

Example

Next, the configuration of a video encoding/decoding system according toan example will be described with reference to FIGS. 5 to 7. FIG. 5 is ablock diagram showing the configuration of a video encoding/decodingsystem according to an example. FIG. 6 is a block diagram showing theconfiguration of a video encoding device according to the example. FIG.7 is a block diagram showing the configuration of a video decodingdevice according to the example.

As shown in FIG. 5, a video encoding/decoding system 100A according toan example includes: a video encoding device (ENCODING DEVICE) 10A; atransmission path (TRANSMISSION LINE) 30 on which the encoded image,which is the output of the video encoding device 10A, is transmitted;and a video decoding device (DECPDING DEVICE) 20A coupled to thetransmission destination. The video encoding device 10A includes anencoding part 11 for encoding an image, a diagnostic image generationpart 12 for generating a diagnostic image, and a switching circuit 13for switching between the input image and the diagnostic image generatedby the diagnostic image generation part 12. The encoding part 11includes a coefficient calculation unit (CC) 111, a local decoding imagegeneration unit (LD) 112, and a variable length encoding unit (VLE) 113.The video decoding device 20A includes a decoding part 21 for decodingthe encoded image, a check signal generation part 22A for generating acheck sum, a storage part 23 for storing the check sum of the diagnosticimage as well as the check sum generated by the check signal generationpart 22A, and a comparison part 24A for comparing the check sumgenerated by the check signal generation part 22A with the check sumstored in the storage part 23. The decoding part 21 outputs the decodedimage (DECODED PICTURE). The transmission path 30 can be a wiredcommunication path or a wireless one. However, the wired communicationpath is preferable in terms of security.

As shown in FIG. 6, the encoding part 11 of the video encoding device10A includes: the coefficient calculation unit 111 including asubtractor 2, an encoder 4, a motion estimation unit 7, and a motioncompensation unit (MC) 8; the local decoding image generation unit 112including a frame store (FS) 3, an adder 5, and a partial decoder 6; andthe variable length encoding unit 113.

The normal image and the diagnostic image are received by an input node1. The subtractor 2 generates the difference between the signal of theinput node 1 and the prediction signal from the motion compensation unit8. Then, the difference is encoded by the encoder 4. The input to theframe store 3 is the sum of the prediction signal, which is generated bythe adder 5, and the encoded differential signal decoded by the partialdecoder 6.

The prediction is achieved by delaying one frame, which is simply doneby the frame store 3. The motion estimation unit 7 compares the frame ofthe image that is currently encoded with the previous frame in the framestore 3. Then, the area in which the target block is the most similar inthe previous frame is identified with respect to each of the blocksobtained by dividing the current frame. The vector difference in theposition between the identified area and the target block is calledmotion vector (MV) because it shows the movement of the object in thescene shown by the displayed image. The vector difference is supplied tothe motion compensation unit 8. The motion compensation unit 8contributes to better prediction by shifting the identified area of theprevious frame to the position of the related block in the currentframe. As a result, the difference formed by the subtractor 2 is smallerin average, allowing the encoder 4 to encode the image by using a lowerrate than the case of larger difference. The variable length encodingunit 113 generates a bit stream based on the output of the encoder 4 andon the motion vector (MV) and outputs to the transmission path 30.

As shown in FIG. 7, the decoding part 21 includes a decoder 6′, a motioncompensation unit 8′, a frame store 3′, and an adder 5′. First, theoperation opposite to every encoding operation performed in the encoder4, is performed in the decoder 6′ to generate an inter-framedifferential signal. The decoder 6′ is similar to the decoder 6. Theinter-frame differential signal is then added to the prediction from theframe store 3′ passing through the motion compensation in the motioncompensation unit 8′ that receives the motion vector (MV) from the videoencoding device 10A. The output of the adder 5′ forms an output of thedecoding part and is supplied to the input of the frame store 3′.

Although not shown, it is also possible to provide a buffer in theoutput of the video encoding device 10A and in the input of the videodecoding device 20A, in order to transmit data over a fixed bit ratechannel.

For example, the video encoding device 10A and the video decoding device20A are semiconductor devices each formed on a single semiconductorsubstrate. Both the video encoding device 10A and the video decodingdevice 20A may be formed on a single semiconductor substrate. In thiscase, the transmission side and the reception side use the samesemiconductor device, in which the transmission side uses only thefunction of the video encoding device 10A and the reception side usesonly the function of the video decoding device 20A. Note that each ofthe video encoding device 10A and the video decoding device 20A may notbe formed on a single semiconductor substrate. Further, the encoding anddecoding may be realized by software on the CPU.

Next, the failure detection operation of the video encoding/decodingsystem according to the example will be described with reference toFIGS. 8 to 12. FIG. 8 is a timing diagram showing the second failuredetection operation of the video encoding/decoding system according tothe example. FIGS. 9 and 10 are timing diagrams for illustrating theeffect of the second failure detection operation of the videoencoding/decoding system according to the example. FIG. 11 is a timingdiagram showing the third failure detection operation (an example usinga part of the input image) of the video encoding/decoding systemaccording to the example. FIG. 12 is a timing diagram showing the thirdfailure detection operation (an example using a part of the input imageby changing the position) of the video encoding/decoding systemaccording to the example.

The video encoding/decoding system 100A according to the exampleperforms the same operation as the first, second, and third failuredetection operations of the video encoding/decoding system according tothe embodiment. The configuration or operation will be described more indetail below.

(1) First Failure Detection Operation

The encoding part 11 encodes the diagnostic image output from thediagnostic image generation part 12 and transmits to the video decodingdevice 20A. The decoding part 21 decodes the encoded image received fromthe video encoding device 10A. Then, the check signal generation part22A generates a check sum of the decoded image. The comparison part 24Adetects a failure by comparing the check sum generated by the checksignal generation part 22A with the expected value (check sum) stored inthe storage part 23 in advance. If the comparison result is a mismatch,the comparison part 24A determines that a failure has occurred andoutputs (or activates) the failure detection signal.

The diagnostic image may be the data stored in a nonvolatile memory suchas ROM or flash memory, or the data written in a nonvolatile memory,such as RAM, or a flash memory from the outside before operation, or thedata that the diagnostic image generation part 12 generates by apredetermined arithmetic operation.

The data for comparison is not limited to the check sum, and checksignals such as hash values, such as MD5 (Message Digest 5) and SHA-1(Secure Hash Algorithm 1), as well as a cyclic redundancy check (CRC)code may also be used. The check sum can also be generated from theimage before de-blocking filter in H.264 (MPEG-4 AVC). It is alsopossible that both the expected value for generating a check sum fromthe decoded image, and the expected value for generating a check sumfrom the image before de-blocking filter are stored in the storage unit23. In this case, whether the check sum is generated from the decodedimage or whether it is generated from the image before de-blockingfilter may be switched according to the setting from the outside, orbased on the signal and data transmitted from the video encoding device10A. Note that the bit stream required for the failure detectionoperation has a data amount of at least about 1K bits, but the check sumhas a data amount of about 100 bits. As a result, the storage cost canbe reduced.

(2) Second Failure Detection Operation

The diagnostic image generation part 12 randomly generates a diagnosticimage. Then, the encoding part 11 encodes the output diagnostic imageand transmits to the video decoding device 20A. The decoding part 21decodes the encoded image received from the video encoding device 10A.Then, the check signal generation part 22A generates a check sum of thedecoded image. The encoding-decoding operation is performed twice on thesame diagnostic image. Then, the comparison part 24A checks if there isa match between the first and second check sums stored in the storagepart 23 in order to perform a diagnosis. If the comparison result is amismatch, the comparison part 24A determines that a failure has occurredand outputs (or activates) the failure detection signal.

As shown in FIG. 8, it is assumed that the first encoding-decodingoperation (failure detection operation) from the A image, which is thediagnostic image, is T(A1) and its second encoding-decoding operation(failure detection operation) is T(A2). Further, it is assumed that thefirst encoding-decoding operation from the B image, which is the nextdiagnostic image, is T(B1) and its second encoding-decoding operation isT(B2). In this case, T(A1), T(B1), T(A2), and T(B2) are performed inthis order. Note that the diagnostic video encoding/decoding operationis performed during the pause period of normal video encoding/decodingoperation (normal operations such as PIC(N), P·IC(N+1), and so on). Whenthe period in which the failure can be detected by the failure detectionoperation from the A image is P(A) and when the period in which failurecan be detected by the failure detection operation from the B image isP(B), there is an overlap between P(A) and P(B).

On the other hand, as shown in FIGS. 9 and 10, when T(A1), T(A2), T(B1),and T(B2) are performed in this order, there is no overlap in each ofthe periods of P(A) and P(B). As a result, a period (P(ND)) occurs inwhich failure may not be detected. By performing the failure detectionoperation in the order of this example, it is possible to eliminate theperiod (P(ND)) of not being able to detect failures.

The random generation method/algorithm can be arbitrary such as a linearfeedback shift register (LFSR). Further, a plurality of predetermineddata can be output periodically.

The encoding-decoding may be performed multiple (three or more) times onthe same diagnostic image. At this time, the operations can be performedin any order as long as there is an overlap in the periods in whichfailure can be detected by the failure detection operations from therespective images.

(3) Third Failure Detection Operation

In the second failure detection operation, failure detection isperformed by the normal video encoding/decoding operation (normaloperation). Apart or whole of the input image is used as the diagnosticimage in place of using the output of the diagnostic image generationpart 12. In other words, in the normal video encoding/decodingoperation, a part or whole of the input image as well as the encodingparameters are stored in the storage part (PICB), and the decodingresult (the check sum generated from the decoded image) is stored in thestorage part 34. Then, the same operation is performed again to obtainthe decoding result (check sum). The comparison part 24A compares theobtained two check sums. If the comparison result is a mismatch, thecomparison part 24A determines that a failure has occurred.

As shown in FIG. 11, PIC(N) and T(N1), PIC(N+1) and T((N+1)₁), T(N₂).PIC(N+2) and T((N+2)₁), T((N+1)₂) are performed in this order. Here, thenormal operation with respect to the N frame is PIC(N), its firstfailure detection operation is T(NO, its second failure detectionoperation is T(N₂). Then, the normal operation with respect to the nextN+1 frame is PIC(N+1), its first failure detection operation isT((N+1)₁), and its second failure detection operation is T((N+1)₂).Further, the normal operation with respect to the N+2 frame is PIC(N+2),its first failure detection operation is T((N+2)₁), and its secondfailure detection operation is T((N+2)₂). T(N₁), T((N+1)₁), and ((N+1)₂)are performed by using a part of PIC(N), PIC(N+1), and PIC(N+2),respectively. When the periods in which failure can be detected by T(N₁)and T(N₂) are P(N) and T((N+1)₁) and when the period in which failurecan be detected by T((N+1)₂) is P(N+1), there is an overlap between P(N)and P(N+1) similarly to the case of the second failure detectionoperation. Thus, it is possible to eliminate the period in which failuremay not be detected.

As shown in FIG. 12, when a part of the input image is used, the failuredetection operation may be performed over several frames by changingpositions. T(Nall) is the first failure detection operation of PIC(N),and uses the whole of the input image. However, the second failuredetection operation is performed separately, for example, three times.T(N₁₂) of the second failure detection operation with respect to T(N₁₁),which is a part of the first failure detection operation, is performedbetween PIC(N+1) and PIC(N+2). T(N₂₂) of the second failure detectionoperation with respect to T(N₂₁), which is a part of the first failuredetection operation, is performed after PIC(N+2). T(N₃₂) of the secondfailure detection operation with respect to T(N₃₁), which is a part ofthe first failure detection operation, is performed after the normaloperation on the N+3 frame. In this way, the failure detection operationof the whole input image of the Nth frame is completed.

When only the third failure detection operation is performed, the outputof the diagnostic image generation part 12 is not used, so that thevideo encoding/decoding system 1 may not include the diagnostic imagegeneration part 12.

The self-diagnosis function of the video encoding/decoding system 100Aperforms failure detection operation by one or a combination of thefailure detection operations (1) to (3). Several examples will bedescribed with reference to FIGS. 13 to 15. FIG. 13 is a timing diagramshowing the operation with a combination of the first and second failuredetection operations of the video encoding/decoding system according tothe example. FIG. 14 is a timing diagram showing the operation with acombination of the first failure detection operation of the videoencoding/decoding system according to the example. FIG. 15 is a timingdiagram showing the operation with a combination of the first and thirdfailure detection operations of the video encoding/decoding systemaccording to the example.

As shown in FIG. 13, the first failure detection operation (1st FAILUREDETECTION) is performed before the start of the video transmission.After the start of the video transmission, the second failure detectionoperation (2nd FAILURE DETECTION) is performed during the pause periodof the encoding-decoding operation. The memory capacity of thediagnostic image generation part 12 or the hardware capacity of thecomputing unit, or the like, must be increased in order to obtainsufficient coverage by only the first failure detection operation. Inaddition, the memory capacity of the storage part 23 in which thecorresponding expected value is stored is large. On the other hand, if afailure occurs before the period in which the first failure can bedetected (for example, before power on or other event), the failure maynot be detected by only the second failure detection operation. Byperforming the second failure detection operation after the firstfailure detection operation, it is possible to reduce the period of notbeing able to detect failures and to reduce the diagnostic imagegeneration part 12 as well as the storage part 23. Further, the secondfailure detection operation can increase the coverage, so that thenumber of times of the first failure detection operation, namely, thediagnosis time before video transmission can be reduced.

The first failure detection operation may be performed only once justafter power on. It is also possible to perform, as shown in FIG. 14, thefirst failure detection operation with an arbitrary interval, in placeof the second failure detection operation, during the pause period ofthe encoding-decoding operation after the start of the videotransmission. This makes it possible to reduce the diagnosis time beforethe video transmission.

As shown in FIG. 15, the respective failure detection operations can beperformed as follows: The first failure detection operation is performedbefore the start of the video transmission. The first operation of thethird failure detection operation (3rd FAILURE DETECTION) is performedduring the normal video encoding/decoding operation. Then, the secondencoding-decoding operation of the third failure detection operation isperformed during the pause period of the encoding-decoding operation.Similarly to the case of performing only the second failure detectionoperation, if a failure occurs before the period in which the firstfailure can be detected (for example, before power on or other event),the failure may not be detected by only the third failure detectionoperation. By performing the third failure detection operation after thefirst failure detection operation, it is possible to reduce the periodof not being able to detect failures and to reduce the diagnostic imagegeneration part 12 as well as the storage part 23. Further, the thirdfailure detection operation can increase the coverage, so that thenumber of times of the first failure detection operation, the diagnosistime before video transmission can be reduced.

Further, the pause period of the encoding-decoding operation can be anarbitrary timing as long as it is not the period of performing thenormal video encoding/decoding operation, such as the vertical blankingperiod between frames, the horizontal blanking period between lines, orthe period that is set by forcibly stopping the encoding-decodingoperation.

The first and second failure detection operations can be performed notonly during the pause period of the encoding-decoding operation, butalso during the normal video encoding-decoding operation period (normaloperation period). In the input of the encoding process in the videoencoding device 10A, the switching between the input image for thenormal operation and the diagnostic image for the failure detectionoperation is performed in a predetermined unit of image area. Forexample, an image obtained by a fisheye lens that covers a wide range istypically subject to the distortion correction process to cut out thefour corners, and is not used for display and image processing. Whensuch an image is the input image, it is necessary to input it byswitching a predetermined image area, such as 20×20 pixels on the lefttop corner, of the unwanted image areas, to the diagnostic image.

Compared to performing the failure detection operation during the pauseperiod of the encoding-decoding operation, there is no need to performthe operation dedicated to failure detection and the power consumptionis reduced.

Applications

The preferred embodiment and example can be applied to the videoencoding/decoding device, the device having the video encoding decodingfunction, and the system using the same. For example, the preferredembodiment and example can be applied to in-vehicle cameras, in-vehicleperiphery monitoring systems, in-vehicle driver support systems,in-vehicle automated driving systems, in-vehicle navigation systems,drive recorders, display audio systems, monitoring camera systems,network cameras, smartphones, tablets, digital cameras, camcorders, settop boxes (STB), Blu-ray Disc (BD) recorders, and the like.

The first to fourth applications (Application Examples 1 to 4) of thepreferred embodiment and example will be described with reference toFIGS. 16 to 19. FIG. 16 is a block diagram showing the configuration ofa video encoding/decoding system according to Application Example 1.FIG. 17 is a block diagram showing the configuration of a videoencoding/decoding system according to Application Example 2. FIG. 18 isa block diagram showing the configuration of a video encoding/decodingsystem according to Application Example 3. FIG. 19 is a block diagramshowing the configuration of a video encoding/decoding system accordingto Application Example 4.

As shown in FIG. 16, a video encoding/decoding system 200A according toApplication Example 1 includes an in-vehicle camera 210A and a controlunit 220A, which is a system in which the in-vehicle camera 210A and thecontrol unit 220A are coupled to an in-vehicle local area network (LAN)230A such as Ethernet Audio Video Bridging (AVB). The in-vehicle camera210A includes an imaging device (CAMERA) 40A and a video encoding device(ENCODING DEVICE) 10, 10A. The control unit 220A includes a videodecoding device (DECODING DEVICE) 20, 20A and a control unit(CONTROLLER) 50A for controlling driver support and automated driving orother functions, based on the decoded image. The video encoding/decodingsystem 200A may further include a display device for displaying thedecoded image.

As shown in FIG. 17, a video encoding/decoding system 200B according toApplication Example 2 includes an in-vehicle camera 210B and a displayunit 220B, which is a system in which the in-vehicle camera 210B and thedisplay unit 220B are coupled by an in-vehicle LAN 230B such as EthernetAVB. The in-vehicle camera 210B includes an imaging device 40B and avideo encoding device 10, 10A. The display unit 220B includes a videodecoding device 20, 20A and a display device (DISPLAY) 60B for displaythe decoded image.

As shown in FIG. 18, a video encoding/decoding system 200C according toApplication Example 3 includes a monitoring camera module 210C and acontrol unit 220C, which is a monitoring camera system in which themonitoring camera module 210C and the control unit 220C are coupled byLAN 230C such as Ethernet. The monitoring camera module 210C includes animaging device 40C and a video encoding/decoding device 10, 10A. Thecontrol unit 220C includes a control device 50C and a video decodingdevice 20, 20A. The video encoding/decoding system 220C may furtherinclude a display device for display the decoded image.

As shown in FIG. 19, a video encoding/decoding system 200D according toApplication Example 4 includes a monitoring camera module 210D and arecorder 220D, which is a monitoring camera system in which themonitoring camera module 201A and the recorder 220D are coupled by LAN230D such as Ethernet. The monitoring camera module 210D includes animaging device 40D and a video encoding device 10, 10A. The recorder220D includes a video decoding device 20, 20A and a storage unit(MEMORY) 70D for storing the decoded image. The video encoding/decodingsystem 220D may further include a display device for displaying thedecoded image.

In the video encoding/decoding systems according to Application Examples1 to 4, it is possible to detect failure in all the paths from the imageinput part of the video encoding device to the image output part of thevideo decoding device. As a result, it is possible to improve safety andreliability.

The invention made by the present inventors has been concretelydescribed based on the preferred embodiment, example, and applications.However, the present invention is not limited to the preferredembodiment, example, and applications. It is needless to say thatvarious modifications and alterations can be made within the scope ofthe present invention.

EMBODIMENTS

A detailed description of the embodiments is added below.

Appendix 1

A video decoding device includes: a decoding part for decoding anencoded image; a check signal generation part for generating a checksignal of the decoded image; a storage part for storing the expectedvalue of the check signal of the diagnostic image, or storing the checksignal generated by the check signal generation part; and a comparisonpart for comparing the check signal stored in the storage part with thecheck signal generated by the check signal generation part.

Appendix 2

The video decoding device according to Appendix 1 performs decoding andcheck signal generation multiple times, respectively, on the samedecoded diagnostic image to compare a plurality of obtained checksignals.

Appendix 3

The video decoding device according to Appendix 2 has a first period forperforming a first decoding and check signal generation on a firstencoded diagnostic image, a second period for performing a seconddecoding and check signal generation on the first diagnostic image, anda third period for performing a first decoding and check signalgeneration on a second encoded diagnostic image. The third period isprovided between the first and second periods.

Appendix 4

The video decoding device according to Appendix 3 compares the checksignal generated in the first period with the check signal generated inthe second period, during the second period.

Appendix 5

The video decoding device according to Appendix 4 has a period fordecoding a normal image, between the first and third periods and betweenthe third and second periods.

Appendix 6

In the video decoding device according to Appendix 5, the check signalis a check sum.

Appendix 7

The video decoding device according to Appendix 1 performs decoding andcheck signal generation multiple times, respectively, on the sameencoded normal image or part thereof to compare a plurality of obtainedcheck signals.

Appendix 8

The video decoding device according to Appendix 7 has a first normalperiod for decoding a first encoded normal image, a first failuredetection period for performing a first decoding and check signalgeneration on the first normal image or part thereof, a second failuredetection period for performing a second decoding and check signalgeneration on the first normal image or part thereof, a second normalperiod for decoding a second encoded normal image, and a third normalperiod for decoding a third encoded normal image. The first failuredetection period is included in the first normal period. The secondfailure detection period is provided between the second normal periodand the third normal period.

Appendix 9

The video decoding device according to Appendix 8 compares the checksignal generated in the first failure detection period with the checksignal generated in the second failure detection period, during thesecond failure detection period.

Appendix 10

In the video decoding device according to Appendix 9, the check signalis a check sum.

Appendix 11

A video encoding device includes a diagnostic image generation part forgenerating a diagnostic image, and an encoding part for encoding thediagnostic image or normal image. The video encoding device performsencoding multiple times on the same diagnostic image or normal image,and transmits to the video decoding device.

Appendix 12

The video encoding device according to Appendix 11 has a first periodfor performing a first encoding on a first diagnostic image and fortransmitting the data to the video decoding device, a second period forperforming a second encoding on the first diagnostic image and fortransmitting the data to the video decoding device, and a third periodfor performing a first encoding on a second diagnostic image and fortransmitting the data to the video decoding device. The third period isprovided between the first and second periods.

Appendix 13

The video encoding device according to Appendix 12 has a period forencoding the normal image, between the first and third periods andbetween the third and second periods.

Appendix 14

The video encoding device according to Appendix 11 has a first normalperiod for encoding a first normal image, a second failure detectionperiod for performing a second encoding on the first normal image orpart thereof, a second normal period for encoding a second normal image,a third normal period for encoding a third normal image, and a secondfailure detection period between the second normal period and the thirdnormal period.

Appendix 15

A video encoding/decoding system includes: an imaging device; a videoencoding device for encoding an image input from the imaging device; avideo decoding device for decoding the encoded image; and a transmissionpath for transmitting the image encoded by the video encoding device,from the video decoding device. The video encoding device includes anencoding part for encoding a diagnostic image or the input image. Thevideo decoding device includes: a decoding part for decoding the imageencoded by the encoding part; a check signal generation part forgenerating a check signal of the decoded image; a storage part forstoring the expected value of the check signal of the diagnostic imageor the check signal generated by the check signal generation part; and acomparison part for comparing the check signal stored in the storagepart with the check signal generated by the check signal generationpart.

Appendix 16

The video encoding/decoding system according to Appendix 15 furtherincludes a control device for controlling driver support or automateddriving based on the image decoded by the video decoding device. Theimaging device is an in-vehicle camera and the transmission path is anin-vehicle LAN.

Appendix 17

The video encoding/decoding system according to Appendix 15 furtherincludes a display device for displaying the image decoded by the videodecoding device. The imaging device is an in-vehicle camera and thetransmission path is an in-vehicle LAN.

Appendix 18

The video encoding/decoding system according to Appendix 15 furtherincludes a control device for performing control based on the imagedecoded by the video decoding device. The imaging device is a monitoringcamera and the transmission path is a LAN.

Appendix 19

The video encoding/decoding system according to Appendix 15 furtherincludes a storage unit for storing the image decoded by the videodecoding device. The imaging device is a monitoring camera and thetransmission path is a LAN.

What is claimed is:
 1. A video encoding/decoding system comprising: avideo encoding device; and a video decoding device, wherein the videoencoding device includes an encoding, part for encoding an imageincluding a diagnostic image or a normal image, wherein the videodecoding device includes: a decoding part for decoding the image encodedin the encoding part; a check signal generation part for generating acheck signal of the decoded image from the encoded image; a storage partfor storing an expected value of the check signal of the diagnosticimage, or storing the check signal generated by the check signalgeneration part; and a comparison part for comparing the check signalstored in the storage part with the check signal generated by the checksignal generation part, wherein the video encoding/decoding systemperforms the encoding, decoding, and check signal generation a pluralityof times, respectively on the same image or part thereof to detectfailure, wherein the video encoding device comprises a diagnostic imagegeneration part for generating the diagnostic image, wherein theencoding device is formed on a first semiconductor substrate, andwherein the decoding device includes the decoding part, check signalgeneration part, storage part, and comparison part that are formed on asecond semiconductor substrate or the first semiconductor substrate,wherein the video encoding/decoding system perform encoding, decoding,and check signal generation multiple times, respectively, on the samediagnostic image to compare a plurality of obtained check signals,wherein the video encoding/decoding system detects failure by comparingthe expected value and a comparison value of the check signals generatedby processing the same image or part thereof a plurality of times,wherein to generate the expected value as a comparison target, theexpected value of the check signal and a comparison value of the checksignal is generated by the check signal generation part, wherein thevideo encoding/decoding system includes: a first period for performing afirst encoding, decoding, and check signal generation on a firstdiagnostic image; a second period for performing a second encoding,decoding, and check signal generation on the first diagnostic image; anda third period for performing a first encoding, decoding, and checksignal generation on a second diagnostic image, between the first andsecond periods, wherein the third period overlaps at least one of thefirst period and the second period when failure is detected, such thatthere is an overlap in periods in which failure is detected fromrespective images.
 2. A video encoding/decoding system according toclaim 1, wherein the check signal generated in the first period and thecheck signal generated in the second period are compared with each otherduring the second period.
 3. A video encoding/decoding system accordingto claim 2, wherein the video encoding/decoding system has a period forperforming normal encoding and decoding, between the first and thirdperiods and between the third and second periods.
 4. A videoencoding/decoding system according to claim 3, wherein the check signalis a check sum, wherein the video encoding device and the video decodingdevice includes a processor that executes computer instructions forencoding and decoding.
 5. A diagnosis method of video encoding/decodingsystem including a first diagnosis step, wherein the first diagnosisstep comprises the steps of: (a1) encoding an image including an imagecomprising a diagnostic image or a normal image; (b1) decoding theencoded image into a decoded image; (c1) generating a check signal ofthe decoded image; and (d1) detecting a failure based on an expectedvalue of the check signal of the diagnostic image and on the checksignal generated in the (c1) step, wherein the detecting of the failureincludes performing the encoding, decoding, and generating the checksignal a plurality of times, respectively, on the same image or partthereof, wherein the first diagnosis step is performed after power onand before video transmission, wherein the detecting of the failureincludes performing the encoding, decoding, and generating the checksignal a plurality of time, respectively, on the same image to compare aplurality of obtained check signals, wherein the detecting of thefailure includes comparing the expected value and the comparison valueof the check signals by processing the same image or part thereof aplurality of times, wherein the expected value of the check signal isgenerated by processing the same image or part thereof a plurality oftimes, wherein the first diagnosis step is performed during a pauseperiod of the encoding and decoding operation of the normal image,wherein a plurality of periods of the encoding, decoding, and checksignal generation are performed on a first diagnostic image, wherein aplurality of periods of the encoding, decoding, and check signalgeneration are performed on a second diagnostic image, and wherein thereis an overlap in periods in which failure is detected from respectiveimages.